"Well, if I don't do twice as well as everyone else, the Vatican comes after me and says that I'm a waste of their time. It's better to study constantly than to be dead, right?"
Seiko Moesashi is a Lower 2nd Class Exorcist of the True Cross Order, and meistered as a Knight . She is the only known daughter of Iblis currently alive in Assiah.
When Seiko was two months old, one of her mother's coworkers reported Seiko and her mother to the Vatican. That led to a big public trial. Her mother pleaded guilty, saying, "I didn't know! " and "She hasn't done anything wrong!" Mephisto Pheles interceded on their behalf, convincing the Grigori to let the girl live as long as she became an exorcist and passed the exorcist exam before her freshman year ended. Later, it was revealed that Mephisto argued for Seiko so that the Vatican would be more lenient at Rin's trial.
When Seiko was in elementary school, her classmates teased her for her ears and her eyes, calling her the "demon cat girl". Seiko told her teachers, but her teachers weren't particularly fond of her either and didn't try very hard to stop the insults. So Seiko would hold the anger in for a few days, and then explode and beat the ringleader up. However, when Seiko was in 7th grade, the Vatican began to fear that she would lose control of her flames at school because she was fighting so often. They sent the current Paladin, Shiro Fujimoto, to her house to execute her and her mother.
Father Fujimoto seemed to be reluctant to execute the Moesashis, but Seiko still went off on a rant about how she wanted to "just be treated as a normal kid for once". Eventually, she lost control of her flames and almost burned the entire house down. Her mother was saved because she had been wearing her True Cross uniform, as she had a mission later that day. Seiko soon lost control over her body to her demonic side.
Moments later, three ghouls were drawn to the Moesashis' by Seiko's flames. Seiko rushed and attacked them but was batted back time after time due to her lack of strategy. Eventually, she hit the wall and coughed up blood. The pain allowed Seiko to wrest control of her body away from the demon inside of her, but also awakened her to the danger of the situation. During a flashback in her freshman year, she thinks, "Here I was, a 12 year-old girl, facing down three ghouls. What could I do? The first ghoul slowly creeped towards my mother and the Paladin, both passed out on the floor. I fell over and began sobbing. What could I do? Nothing. I was useless. Ghouls could only be killed by silver or a powerful firearm, and I had neither."
Seiko then realized that the exorcist badges are made of holy silver, and tied her mother's badge to Hibana, her right-hand sword. She used this to slay one of the ghouls, and smashed the other's face against the Paladin's badge and held it there. She exorcised the last demon using one of Father Fujimoto's machine guns. Seconds later, Father Fujimoto woke up. After he found out that she slew all three ghouls on her own, her declared that the Grigori was wrong to give the execution order, saying that it would be "a waste of a good exorcist". Together, he and Seiko revived Hikaru Moesashi. Father Fujimoto also managed to convince the Grigori with Mephisto Pheles's help not to kill Seiko.
Seiko is a very sarcastic person, which stems from her being bullied for her appearance when she was younger. She also has a good work ethic, because if she doesn't work harder than everyone else the Vatican sends someone to execute her. Seiko doesn't like to depend on other people, even to the extent of telling Yukio after she passes out on her kitchen floor that he didn't need to bring her to the hospital.
Seiko has shoulder-length black hair and brown eyes colored so dark that they look almost black. Her pupils look like slits and her ears are pointed, which earned her the name "demon cat girl" in elementary school and junior high . She often has her twin swords, Hibana and Kaen, strapped to her back and a messenger bag with other supplies.
Hikaru Moesashi: Seiko's mother. Their relationship is rarely mentioned, though it is implied that Seiko's mother loves her.
Iblis: Seiko's father. Seiko has never met him, but hates him because she was bullied for being the daughter of Iblis in elementary school and junior high.
Seiko inherited the flames of Iblis, which are able to come into Assiah when she draws one or both her swords. Seiko also excels at fistfighting, as she would get into many fights in elementary school and junior high.
Seiko posesses two demon short swords given to her by her father. The right-hand one is called Hibana, and the left-hand one is called Kaen. When Seiko draws one, her flames appear in half of their total intensity, when she draws both, the flames appear in their full intensity. For this reason, Seiko ranks the difficulty exorcisms as "single blade" and "dual blade" difficulties, and doesn't draw both blades unless she truly needs to.
Plot during anime series
During the series, Seiko's mother is called to True Cross Academy to assist in the evacuation of humans. Seiko comes along and helps her mother.
After the series
Red Exorcist Chapter 2
Seiko first appears at the Academy during Rin and Yukio's senior year. She arrives two days before cram school starts, and reveals to us that her mother forced her to stay in a villa on the outskirts of campus instead of in one of the dorms, because Mephisto was giving her a full ride scholarship. When Seiko arrives, Mephisto appears in front of her in dog form. Seiko immediately says, "I don't know who in Gehenna you are, but I'll just assume that Mephisto sent you here to spy on me." Mephisto changes into his human form, and when Seiko asks him what he would do if she were changing in another room, he replies that he would find her and stare at her until she was finished. Seiko calls him " 'a sick, perverted pedophile' ". 
Red Exorcist Chapter 3
Because Seiko began training so early, she is put in Yukio's class in the cram school. Her classmates don't believe that she is supposed to be in that class until Izumo reads Seiko's schedule out loud to the class. After that, it is announced that Seiko is a daughter of Iblis, and during lunch that day, Seiko says, "If I don't do better than everybody else, than the Vatican comes after me and says I'm a waste of their time. It's better to study my butt off than be dead, right?" Her classmates all say that her situation is awful, to which Seiko repleis that it's reality, and reality isn't " 'all happiness and sparkles.' " After that everyone falls silent, and Izumo complains that Seiko has turned the atmosphere serious, and Rin didn't turn the atmosphere that silent because he was too busy fooling around. Seiko blames Suguro for asking her why she was in an advanced class, and Suguro retorts that she didn't need to give such a serious answer. Konekomaru says that Yukio is trying to reform the Vatican, and once he does, " 'Moesashi-san can slack off all she wants and we can catch up to her. ' " Seiko retorts that she would never slack off, and that reforming the Vatican is almost impossible because the old laws have already been in place for so long. Rin says that Yukio can do it, or " 'he'll die trying.' " After Rin finishes speaking, the bell rings, signaling the end of lunch.
Red Exorcist Chapter 4
Shortly after the regular school year starts, Mephisto calls Seiko to his office and tells her that she'll be taking classes in using demon blades with Rin and Shura. He says that Seiko and Shura will " 'get along beautifully,' " though Seiko suspects that Mephisto really means the opposite.
When Seiko meets Shura, her first impression of her is that Shura is a slacker who does nothing but drink beer all day, and the only thing they have in common is their disbelief that Rin will become Paladin. When Rin shows up to class late and asks Seiko why she's in his class, she jokes, " 'Training and wondering what Shura's liver looks like, same as you.' " Rin says that he doesn't understand the joke, and Seiko asks if he didn't study science in 6th grade. Rin says he started skipping class in 5th grade, causing Seiko to call him an idiot. RIn challenges her to a fight, and Seiko says that she thought that he would have better manners to challenge a girl two years younger than him to a fight. Shura then comes in and scolds Rin for slacking off.
A few weeks later, Shura begins teaching Seiko how to use her swords to do special techniques. Seiko learns two techniques, one of which she uses in Chapter 5.
Red Exorcist Chapter 5
A trimester passes with almost nothing happening, though Seiko says that the seniors do hold a joint birthday party where they celebrate everyone's birthday. They tell her that it's easier than celebrating everyone's birthday seperately and more fun.
A week after break, Yukio knocks on Seiko's door, saying that a group of hobgoblins and ghouls have gotten inside the campus, and because everyone else is either running a border check or exorcsing the other demons, she and Yukio are needed to exorcise one of the hobgoblins, which Yukio grimly says is a level five. When Seiko asks why she is helping instead of Rin, Yukio says that she's more reliable. Seiko thinks it sounds suspicious, but brushes it off.
Yukio and Seiko arrive at where the hobgoblin is located, which is the ferris wheel in MepphyLand. Yukio tells Seiko to lure the demon to the food booth and trap it there. Once it is in, Yukio will start firing from a hole on the roof. Seiko only draws one sword, expecting the demon to be single blade difficulty, though when she sees it has a crown on its head she quickly realizes that she'll need both blades to defeat the hobgoblin. She draws Kaen, and decides that the best way to lure the demon to the food booth would be to steal its crown. However, her first attmept ends unsuccesfully, with Seiko getting swiped off of the hobgoblin's head.
Seiko tries again, and when she is batted back, she fakes unconciousness. When the demon comes to finish her off, Seiko runs up its arm onto its head and nabs the crown. She runs into the food booth and once the hobgoblin is in, jumps out and uses the Ring of Fire technique to trap it inside. Yukio fires until th demon is defeated, and then congratulates Seiko on a job well done. Mephisto then appears above them on his flying chair, and reveals that the mission was her exorcist exam in disguise. Seiko is initially furious that the two of them set her up, but decides to let it go. Mephisto tells her that she'll be serving as a TA for the rest of the year, and then thanks her for not destroying the booth, saying, " 'it costs a lot of money to replace, you know.' " Seiko says " 'You're welcome' ", though she shares that ' "everyone in the Order knew that Mephisto had enough money to replace the damn booth.' "
Red Exorcist Chapter 6
Seiko is walking to her next period when she overhears a conversation between Mephisto and Yukio about Jacob's Ladder. Yukio catches her eavesdropping and tells Seiko to forget the conversation because it will only disturb her and lower her grades. Seiko nods and runs to her next period, sliding into her seat just as the bell rings.
After cram school has ended, Seiko confronts Yukio about the conversation. Yukio reveals that Egin's disciples want to create another Jacob's Ladder, and will need Rin, Yukio, and Seiko's blood to complete the project. Yukio tells Seiko that she is powerless to stop this, and tells her to just live her life as if nothing happens.
When Seiko comes back to her villa, she muses over how useless she is. This leads to a flashback of her near execution, and therefore, the only time she lost control of her flames and the first time she felt useless. After the flashback, Seiko blacks out and falls onto her kitchen floor.
Red Exorcist Chapter 7
Seiko wakes up in the hospital. She initially thinks that she's in heaven, but brushes away the possibility because she's a demon. She looks around the room, and sees Yukio sitting by her bed. Seiko then learns that it is the next day, and tries to get out of bed because she has lessons with Shura. Yukio pushes her back down, and he and Seiko argue about whether or not she should go to classes. Seiko then realizes that Yukio brought her to the hospital, and immediately feels guilty for arguing with him. Then they begin arguing about whether or not Yukio was obligated to bring her to the hospital.
Mephisto enters, and says that Seiko and Yukio are "fighting like an old married couple". Yukio and Seiko both blush, and Seiko jabs back with, "What are you saying, clown?" Mephisto remarks that her jabs are jsut as lively as ever, and Seiko clutches her head to ward off an impending flashback. Yukio asks if she's okay, and Seiko snaps, but apologizes right after. Mephisto gives Seiko a golden chibi statue of him, a box of chocolates, and a key to the supply shop as a "get-well present", then leaves. Yukio asks Seiko why she passed out, and Seiko tells him the story of her childhood, starting with her first day of preschool and ending with her seventh grade year.
After Seiko finished talking, Yukio falls silent. Seiko prompts him to say something, and Yukio confesses his feelings for Seiko and hugs her. The two kiss for the first time, and Seiko describes it as "strangely sweet". When they break apart, Mephisto comes through the door announcing a staff meeting, but tells Yukio to take his time. Seiko tells Yukio to go to the staff meeting, and that she'll be waiting for him when he comes back. Yukio leaves the room.
- In progress
- Character should not date Yukio.
- ↑ https://www.fanfiction.net/s/11100519/1/Red-Exorcist
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 https://www.fanfiction.net/s/11100519/6/Red-Exorcist
- ↑ 3.0 3.1 3.2 https://www.fanfiction.net/s/11100519/7/Red-Exorcist
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 https://www.fanfiction.net/s/11100519/5/Red-Exorcist
- ↑ https://www.fanfiction.net/s/11100519/9/Red-Exorcist
- ↑ 6.0 6.1 6.2 https://www.fanfiction.net/s/11100519/2/Red-Exorcist
- ↑ https://www.fanfiction.net/s/11100519/3/Red-Exorcist
- ↑ 8.0 8.1 8.2 8.3 https://www.fanfiction.net/s/11100519/4/Red-Exorcist